I looked around a lot i cant seem to find any places where to change key bindings ! idem for changing the annoying pure white background-floor+sky color

Also i wanted to change the default color of joints to something more distinguishable than the default "orange" and "less-orange" ! something like red-relaxed, green-pulling .. but i cant find it in the options menu (I'm not talking about texture images here just the base color)

DID YOU NOTICE when your mouse hovers over a relaxed side of a joint it highlights the joint making the less-orange color the same as the other state of the joint! really a nuisance!

so... theses things are NOT hard/long to implement so i guess there should be a way to change them somewhere... but i cant find it in the config/options menu!
please help!

I suggest having a look here:
The ultimate guide to unleashing the true potential of your custom folder.

The Item.dat section will probably help you out the most. There you can change the colours of your joints and other equipment there without having to purchase the item itself. (It won't work in Multiplayer though!)

If you want to have different coloured joints in multiplayer you'll have to buy them like the rest of us.